What is in this article?:
- Insect problems in Alabama cotton are taking a backseat to weed and disease issues.
- Stink bugs still could pose a threat under certain conditions.
- Determining an accurate threshold is important in stink bug management.
AUBURN UNIVERSITY EXTENSION Entomologist Ron Smith discusses cotton insect pests with a participant at the recent Cotton & Soybean Scout School held in Autaugaville, Ala.
“These can be seen in tremendous numbers, and their damage is indistinguishable from that of the stink bug. The immatures are orange in color and they come out of an egg mass. You can find them in an old garden with old tomato plants.”
Stink bugs sometime damage the entire boll, says Smith, but more than likely, they’ll get one or two locks out of a boll. Anything from a normal boll to a partially damaged boll is possible with this insect pest.
“We do change the threshold level as we move through the summer. We want to pull 25 bolls that are about the size of a quarter and soft to the touch. We then get a percentage of the damaged bolls.”
First of all, crush only the bolls that have external damage, advises Smith.
“If you reach the threshold, then you don’t even have to crush the remainder of the bolls. It’s a faster way of doing it.
“If you don’t get a threshold by just crushing the ones with external damage, go ahead and crush the rest of the bolls.
“A lot of times, if we get real stink bug problems in the summer, you’ll reach a threshold by crushing just the bolls with external damage. It’s slow crushing those bolls, especially if you’re in the commercial scouting business.”
Internal damage is most important, he says.
“At week 1 and 2 of bloom, we can let 30 to 50 percent damage go before you call it a threshold. Weeks 3, 4, 5 and 6 are the critical weeks for stink bug injury in cotton.
“That’s also the month when you make the most bolls. As cotton is maturing out, and you find fewer and fewer bolls that are soft to the touch and are 10 to 12 days old, then you rate your threshold.”
Research has not shown any yield increase by spraying 10 percent early or 10 percent late, he says.
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